A Male Maid of Honor?

The very word maid indicates an unmarried woman, so the answer would appear to be yes. Even so, these marriage customs are not directly related to Catholic teaching or the requirements of the Church for a valid marriage. All the Church requires is marriage before a priest or deacon (only a priest in the Eastern rites) with two witnesses, who may be male or female.

There is no Church law requiring the observance of such cultural customs as are usual—that is, of best man or matron or maid of honor. So the basic Catholic answer is that you are not required to have a maid of honor at all, but that being said, “maid” does mean a woman, not a man.